1. Field of the Invention
This invention relates generally to a torque measuring apparatus and in particular to an apparatus which measures the running torque of a low-friction bearing when the bearing is running at a known speed and radial load.
2. Description of the Prior Art
In many applications low-friction bearings are typically loaded in a radial direction. Thus, in designing equipment which utilizes such low friction bearings it is desirable to have a measure of the running torque (also known as drag torque) of the bearing while the bearing is running at a known speed and radial load. The difficulty, however, in obtaining this type of measurement lies in designing a device which will be heavy enough to apply the required radial load yet be sufficiently sensitive to accurately measure the running torque in a low-friction bearing. Bearing manufacturers avoid this problem by applying an axial load to the test bearing. A typical bearing tester is disclosed by Wadsworth in U.S. Pat. No. 2,928,275. The tester disclosed by Wadsworth applies an axial load to a test bearing and measures the running torque indirectly through elapsed time. Other bearing testers which do apply a radial load to the test bearing also include an extraneous torque in each measurement. Accordingly, it is desireable to provide an apparatus for measuring the running torque of a bearing while the bearing is under an essentially radial load.